Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
  • F02P5/00—Advancing or retarding ignition; Control therefor
  • F02P5/04—Advancing or retarding ignition; Control therefor automatically, as a function of the working conditions of the engine or vehicle or of the atmospheric conditions
  • F02P5/145—Advancing or retarding ignition; Control therefor automatically, as a function of the working conditions of the engine or vehicle or of the atmospheric conditions using electrical means
  • F02P5/15—Digital data processing
  • F02P5/152—Digital data processing dependent on pinking
  • F02P5/1521—Digital data processing dependent on pinking with particular means during a transient phase, e.g. starting, acceleration, deceleration, gear change
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
  • F02P5/00—Advancing or retarding ignition; Control therefor
  • F02P5/04—Advancing or retarding ignition; Control therefor automatically, as a function of the working conditions of the engine or vehicle or of the atmospheric conditions
  • F02P5/145—Advancing or retarding ignition; Control therefor automatically, as a function of the working conditions of the engine or vehicle or of the atmospheric conditions using electrical means
  • F02P5/15—Digital data processing
  • F02P5/152—Digital data processing dependent on pinking
  • F02P5/1523—Digital data processing dependent on pinking with particular laws of return to advance, e.g. step by step, differing from the laws of retard
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/40—Engine management systems

Definitions

• the invention relates to a knock control system of a spark ignition internal combustion engine according to the precharacterising clause of claim 1.
• a further known optimisation in terms of low fuel consumption and low pollutant emission is achieved in that the i.e. engine in the upper load and speed range is operated close to the knock limit. Since the position of the knock limit is variable and is dependent upon operating parameters, in particular upon the motor fuel quality, temperature and air pressure, it is known practice to effect knock control in the manner of short-time control.
• the characteristic map input read out from the filed characteristic map is reset by one control stroke in the direction of retarded ignition to a value for the actual ignition point.
• the value for the actual ignition point is moved by one control stroke in the direction of advanced ignition back to the characteristic map input.
• Said short-time control is therefore related to the level of the filed characteristic map input.
• the knock limit may be relatively remote from the characteristic map input, with the result that control is operated with correspondingly large control strokes and a wide control band width. This is disadvantageous for control stability so that control is achieved at the price of relatively high number of detonating combustions with, in some cases, violent knocking. This has an adverse effect both on the material and on optimum running as well as affecting acoustic comfort through, to some extent, audible knocking.
• characteristic maps which are determined from the outset, and to make said maps available as and when required.
• it is known, for example, by changing a connector in the engine area to switch from a specific characteristic map allocated to running on supergrade fuel to a second preset characteristic map for use when running on regular fuel.
• the aim of the invention is to reduce the incidence of knocking and to keep knock control more stable as a whole.
• long-time adaptation is effected in that, on occurrence of instances of knocking, the characteristic map input is reset or modified by an adaptation value away from the knock limit so that short-time control is referred to a new ignition point input (characteristic map input plus adaptation value) or to a different level.
• the adaptation values are acquired in dependence upon the instances of knocking occurring within specific recurring monitoring intervals.
• the reference level for control is advantageously newly acquired within the recurring monitoring intervals and in dependence upon the instances of knocking occurring therein, and the control range or the control band width and hence the knock limit should only be a slight distance from said reference level.
• the position of said reference level is varied in that suitable acquired adaptation values are added to the values from the filed characteristic map.
• each cylinder of the i.e. engine is allocated its own characteristic maps and knock control with the adaptation according to the invention is effected in a cylinder-selective manner.
• each of the cylinders may be operated separately in the thermodynamically optimum manner, thereby making it possible to keep fuel consumption and pollutant emission to a minimum.
• the adaptation values are acquired by taking the mean of all the control strokes arising in a monitoring interval.
• Said mean value variable also provides a suitable indication of the position of the knock limit and hence an adaptation and retracing of the reference level for short-time control.
• the knock limit is not a precisely defined limit but is to be regarded as a statistical limit, with it also being possible for instances of knocking to occur above or below the acquired knock limit depending upon the quality of combustion at the time. Since the position of the knock limit is therefore not a precisely defined variable anyway, claim 7 proposes that an adaptation should only be effected when the mean value of the control strokes is above the value of a fixed threshold. This means that an adaptation should only be effected in the event of a major deviation from the statistically acquired knock limit. Adaptations which would be effected on account of the statistical band width of the knock limit are therefore excluded and the adaptation processes and hence the entire knock control process are stabilised.
• Claim 8 indicates a concrete specification for acquiring an adaptation value from a mean control stroke.
• a new adaptation value (L Znew ) is to be calculated by adding the previous adaptation value (L Zold ) to the mean control stroke.
• a preset threshold value (S) is
• the reference level for stabilising control is not to be placed precisely at the knock limit acquired by the mean control stroke but is shifted by the threshold value (S) in the direction of advanced ignition.
• S threshold value
• a suitable control band width for short-time control is thereby made available, with instances of knocking which are statistically far above the knock limit in the direction of advanced ignition being truncated and not being taken into account in the control process.
• An adaptation should only occur when the mean control stroke is greater than a threshold value (S), with it being possible for said threshold value to be equal in size to the preceding one.
• a suitable threshold value is, for example, 0.75° KW.
• preset increment values are added on each occurrence of knocking within a monitoring interval and an adaptation value is thereby acquired.
• the adaptation value is only to be reset by the restoring variable if there are no instances of knocking at all in the monitoring interval but the mean control stroke and the sum of the increment values in a monitoring interval are less than the value of a threshold.
• a suitable threshold value for this threshold too is, for example, 0.75° KW.
• a suitable monitoring interval comprises or refers, according to claim 12, to at least 500 ignitions.
• Fig.1 a diagram in which the adaptation of a reference level
• Fig.3 a test record relating to the ignition points and adaptations of four cylinders of an i.e. engine.
• the value of the ignition angle ⁇ z with the direction towards advanced ignition is plotted upwards against the rightward pointing time axis.
• the horizontal dashed line corresponds to a characteristic map input 1 for the ignition point from a permanently filed characteristic map.
• a fixed operating state at a specific operating point i.e. for example, fixed load and fixed speed, is being considered, so that the characteristic map input 1, viewed with respect to time, remains constant.
• an adapted characteristic map input 3 is then introduced as a new reference level for short-time control in that the characteristic map input is reset in a type of regulation relative to the new knock limit in dependence upon the incidence of knocking to the adapted value 3, as is diagrammatically indicated by the arrow 4. Said resetting is achieved in that the original characteristic map input 1 is acted upon by a variable adaptation value (L Z ).
• the adaptation value (L Z ) is acquired within specific recurring monitoring intervals in dependence upon the knocking incidence, with ignitions in the order of magnitude of 500 ignitions arising in one monitoring interval.
• Suitable adaptation values are obtained by taking the mean of the control strokes arising in the monitoring interval, with it being possible to use either only the control strokes on occurrence of an instance of knocking or all the control strokes carried out in the monitoring interval.
• a suitable adaptation value may also be obtained in that, upon each instance of knocking, an increment value is output and said values are added up.
• a change in an adaptation value (L Z ) is only effected when the mean values obtained are above a specific threshold (S). This is shown in the left half of Fig.2. With the "increment system", a specific increment value is always added upon detection of knocking. For restoring of the ignition points, a monitoring interval is again defined in which no instance of knocking (or only a limited number of instances of knocking) has been detected.
• threshold value may advantageously correspond to the previous threshold value.
• a previous adaptation value (L Zold ) is then reduced by a restoring value ( ⁇ L K ) to a new adaptation value (L Znew ) when no instances of knocking are detected in the new monitoring interval or their mean value is less than the preset threshold.
• Fig.3 shows an actual test record for four cylinders of an i.e. engine in which the actual ignition point is plotted against time.
• the continuous horizontal lines represent the filed characteristic map input for each cylinder.
• control runs in the direct vicinity of the characteristic map input and so, in this case, control is operated in the optimum manner from the start. This may be caused, for example, by the fact that the first cylinder, being
• interval I no adaptation value has yet been acquired and the control band width, with many fluctuations, is relatively great.
• the ignition points are at approximately the same level with more stable control with a reduced control band width.

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• Engineering & Computer Science (AREA)
• Signal Processing (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Electrical Control Of Ignition Timing (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 1990
  • 1990-01-19 DE DE4001474A patent/DE4001474A1/de not_active Ceased
  • 1990-12-18 WO PCT/EP1990/002223 patent/WO1991010829A1/en active IP Right Grant
  • 1990-12-18 EP EP91900750A patent/EP0511220B1/de not_active Expired - Lifetime
  • 1990-12-18 JP JP3501242A patent/JPH05504388A/ja active Pending

Non-Patent Citations (1)

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